Under the hood, there are two kinds of integers—small integers,
called *fixnums*, and large integers, called *bignums*.

The range of values for a fixnum depends on the machine. The minimum range is −536,870,912 to 536,870,911 (30 bits; i.e., −2**29 to 2**29 − 1) but many machines provide a wider range.

Bignums can have arbitrary precision. Operations that overflow a fixnum will return a bignum instead.

All numbers can be compared with `eql`

or `=`

; fixnums can
also be compared with `eq`

. To test whether an integer is a fixnum or a
bignum, you can compare it to `most-negative-fixnum`

and
`most-positive-fixnum`

, or you can use the convenience predicates
`fixnump`

and `bignump`

on any object.

The read syntax for integers is a sequence of (base ten) digits with an
optional sign at the beginning and an optional period at the end. The
printed representation produced by the Lisp interpreter never has a
leading ‘`+`’ or a final ‘`.`’.

-1 ; The integer −1. 1 ; The integer 1. 1. ; Also the integer 1. +1 ; Also the integer 1.

See Numbers, for more information.